What is aflatoxin?

11th Nov, 2019

Aflatoxin infected maize and peanuts. Photo: foodsafetytrainingcertification.com

Aflatoxins are naturally occurring cancer-causing toxins produced by a mould fungus that attacks crop such as maize, peanuts, cottonseed and tree nuts, according to online publication cancer.gov

The main fungi that produce aflatoxins are Aspergillus flavus and Aspergillus parasiticus, which are abundant in warm and humid regions of the world such as Kenya.

The aflatoxin fungi contaminate crops while on the farm, during harvesting, during storage or during processing.

Aflatoxin is commonly found in poorly stored food crops such as cassava, chilli peppers, millet, rice, sorghum, sunflower seeds, beans, cocoa beans, soya beans, coffee beans, wheat and hay.

The natural habitat of fungus causing aflatoxin Aspergillus is in the soil, dead, decaying vegetation, airborne spores, hay and grains and thrives in conditions that favour its growth such as high moisture content and high temperatures.

According to the Centre for Food Safety of the Food and Public Health Branch of the Food and Environmental Hygiene Department of HKSAR Government cfs.gov.hk, the accumulation of aflatoxin depends on the weather conditions such as drought and prolonged exposure to high humidity.

Before a farmer harvests, the risk for the development of aflatoxin is greatest during major droughts when the soil moisture is below normal and temperatures are high.

The number of Aspergillus spores in the air increases and they infect crops through damaged areas caused by insects, pests and unfavourable weather. 

Once infected, the plant resistance weakens and the production of aflatoxin is favoured. 

Farmers and other agricultural workers may also be exposed by inhaling dust generated during the handling and processing of contaminated crops and feeds with aflatoxin notes foodsafetytrainingcertification.com

How it is spread

When contaminated food is processed or consumed, aflatoxins pass through the food chain to humans.

Aflatoxin spreads from infected crops to human or to animals then to animal products before human consumption. Photo: US National Library of Medicine National Institutes of Health

Infected animals produce infected products such as dairy products like milk, eggs and meat from poultry such as chicken, turkey, dairy or beef cattle, pigs and fish.

Aflatoxins are usually stable in foods and are resistant to degradation under normal cooking procedures.

Human beings are exposed to aflatoxins when they consume food flour products from maize, sorghum, wheat such as ugali, bread, beer processed from contaminated crops.

Only 20 parts per billion are intended for human food according to the Food and Drug Administration of the United States according to uaex.edu.

Pregnant mothers risk transmitting aflatoxins to the unborn child and the newborn through breastmilk.

Effects on human

Overexposure to aflatoxins is associated with increased risks of contracting cancer such as liver and gall bladder cancer.

Children are particularly affected by aflatoxin exposure, which is associated with stunted growth, delayed development, liver damage, and liver cancer notes wikipedia.org.

Adults, however, have a higher tolerance to exposure but overexposure has high fatal risks from liver damage, liver cirrhosis and reduced immunodeficiency.

Large consumption of aflatoxin causes poisoning which can be life-threatening and damages the liver immediately causing its failure.

Testing of aflatoxin 

Human aflatoxin levels are measured by taking a specimen of urine or mainly blood which gives the best results in terms of long term exposure.

A sampling of aflatoxins causing moulds in crop produce is usually difficult as they are not evenly distributed throughout stored grains thus there is a need to develop a rapid, low-cost, low technology, accurate detection methods to improve surveillance and control in rural areas notes the World Health Organization Food Safety Digest.

Control measures

Consumers can avoid or reduce aflatoxin exposure by buying accredited products and ultra-heated dairy products that undergo chemical processes to remove the aflatoxins.

Farmers can avoid the moulds spread or growth through proper drying and storage practices that minimize exposure of food crops to the aflatoxins that occur in hot and humid conditions.

Farmers can also treat their organic crops with fungicides to prevent fungal moulds.

Livestock should also not be fed with feeds that exceed the set parts per billion to avoid aflatoxin effects.

Peanut butter making machines can also become contaminated with aflatoxin.

The peanuts to be ground may also contain aflatoxin, which can increase during storage.

It is highly recommended peanut butter machines are thoroughly cleaned daily as they can become breeding grounds for the Aspergillus moulds. 

Regular intake of vegetables such as carrots, celery may reduce the harmful effects of aflatoxin.

Consumers should never consume any mouldy food to avoid being infected.

The government should also put more measures to ensure that aflatoxins levels in the country in terms of parts per billion are reduced in food and food products before they are sold for human consumption.

Consumers are advised to be diverse in the food they consume to prevent high toxic exposure of aflatoxin in their everyday meals.

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